First used in Drosophila, recombination frequencies can help map relative positions of genes along chromosomes. The greater the distance between two loci on a single chromosome, the greater the chance that they will be separated by a crossing-over event during meiosis I. If two genes are recombined in x% of gametes, they are separated by a genetic map distance of xmap units. In humans, such mapping located disease-causing mutations near single-nucleotide polymorphisms (SNPS). Recombination frequencies among six Drosophila chromosome genes (yellow-body (yb), white-eye (we), singed-bristle (sb), miniature wings (mw), round eyes (re), and hairy body (hb) are given in the table below. Using this information, place the genes in the correct relative order along the chromosome. Genes we and yb have been filled in to get you started. we yb sb mw re hb we 1.4 19.6 34.7 6.1 12.3 yb 1.4 21 36.1 7.5 13.7 sb 19.6 21 15.1 13.5 7.3 mw 34.7 36.1 15.1 28.6 22.4 re 6.1 7.5 13.5 28.6 6.2 hb 12.3 13.7 7.3 22.4 6.2 Note that the targets are not drawn to scale. |singed-bristle (sb) B) miniature wings (mw) round eyes (re) yb we | hairy body (hb)

Here is a strawberry karyotype - ignore the different colours. How many chromosomes are shown in the figure? What is the ploidy of this type of strawberry? How many alleles could an individual strawberry have at each locus? Finally during the G2 stage of cell division, how many double helixes would be in this picture if you drew them over the chromosomes? Many domesticated plants are polyploid - give one possible reason why this might be the case, with a focus on using genetic principles to reason it out (i.e., you don't have to be right per se, you have to build an argument based on what you've already learned).

A line of mouse cells is grown for many generations in a medium with 15N. Cells in G1 are then switched to a new medium that contains 14N. Draw a pair of homologous chromosomes from these cells at the following stages, showing the two strands of DNA molecules found in the chromosomes. Use different colors to represent strands with 14N and 15N. Q. Cells in anaphase II of meiosis, after switching to medium with 14N

Species I has 2 n = 16 chromosomes. How many chromosomes will be found per cell in  the following mutants in this species? Q. Autotetraploid

A diploid species has 3 pairs of chromosomes in its somatic cells. In males, the first pair is large submetacentric[1]; the second is medium acrocentric[2], and the third is small telocentric[3].  In females, the first two pairs are like those of the males while the third is large metacentric[4][5], with satellite4 Illustrate the karyograms (drawing/picture of the chromosome) of the following:   A triploid cell in females         tetrasomic cell in males         tetraploid cell in females     [1] submetacentric --centrosome is just above the middle of the chromosome  [2] acrocentric --centrosome is much higher location than submetacentric  so that the “p” arm of the chromosome is much shorter than the q arm [3] telocentric --the centromere is at the end of the chromosome [4] metacentric --centrosome is in the middle of the chromosome; thus the “p-arm” and the “q-arm” or both arms of the chromosome are equal in length [5] satellite-a constriction in an arm of a chromosome, aside…

Researchers have discovered that some regions of chromosomes are more likely than others to cross over, these areas of frequent crossing over are called "recombination hot spots". Gene A and B are 500,000 bp apart - the genes are either side of a recombination hot spot. Gene C and D are also 500,000 bp apart but the region containing genes C and D are not near a recombination hot spot. Would the map distance between A and B be the same as the map distance between C and D? Explain your answer.

A D. melanogaster male is homozygous for a translocation between chromosomes 2 and 3.  This fly is otherwise wild-type.  This male is crossed to a female fly that is homozygous for normal chromosome order and is homozygous for dumpy wings (dy), a recessive on chromosome 2 and sepia eyes (se), a recessive on  chromosome 3. A male progeny from the above cross is test-crossed to a female fly that is homozygous for dy and se.  What progeny phenotypes and frequencies are expected from this second cross? Answer choices 1/2 wild-type and 1/2 dumpy and sepia 1/4 wild-type, 1/4 dumpy, 1/4 sepia, 1/4 dumpy and sepia All dumpy and sepia                       2/3 wild-type, 1/3 dumpy and sepia 9/16 wild-type, 3/16 dumpy, 3/16 sepia, 1/16 dumpy and sepia